EWG's Tap Water Database — 2021 UPDATE


Xylenes (total)

Williamson County Wsid 3

Xylenes are solvents used in industrial and consumer products, such as cleaning agents and paint thinners. Xylenes cause nervous system damage and may harm developing fetuses.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20140.525 ppb41ND - 2.10 ppb
201533.4 ppb106ND - 161.0 ppb
20164.43 ppb71ND - 31.0 ppb
20174.14 ppb71ND - 29.0 ppb
20181.31 ppb73ND - 6.50 ppb
20190.529 ppb74ND - 1.20 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 1,800 ppb

The EWG Health Guideline of 1,800 ppb for xylenes was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against harm to the brain and nervous system.

EPA Maximum Contaminant
Level (MCL) 10,000 ppb

The legal limit for xylenes, established in 1991, was based on a toxicity study in laboratory animals conducted in the 1980s. This limit may not fully protect against harm to the brain and nervous system due to xylene exposure.

ppb = parts per billion

All test results

Date Lab ID Result